Amplifiers and equalizers are commonly used in high-speed circuits. For short-channel applications, simple amplification may suffice. For long-channel application, equalizers may be used to boost certain spectral portions of the signal relative to other portions.
Voltage gain amplifiers (VGAs) and continuous-time linear equalizers (CTLEs) can be used to compensate signal losses. To minimize distortion, a configuration of a CTLE following a VGA can be used. However, such a configuration diminishes the overall bandwidth. Additionally, some traditional VGAs use source degeneration variable resistors for gain control. However, parasitic capacitor effect produces unwanted high amplitude in gain (overpeaking) in the high-frequency ranges of the frequency response. While certain traditional modifications of VGAs may reduce such overpeaking, such modifications can lead to degradation of the overall bandwidth.
Efforts in designing amplifiers and equalizers with improved characteristics are therefore ongoing.